With an ever-growing elderly population, it is becoming increasingly important to monitor physiological correlates associated with age. One major problem associated with age revolves around quantity and quality of sleep. Many commercial devices monitor physiometric nocturnal activity (i.e. actigraphy, EEG, EMG, EOG, respiration, etc.), however, there are no commercial devices available for continuous, non-invasive, near real-time monitoring of chemicals in the blood. The pineal hormone, melatonin, follows a characteristic circadian temporal pattern. Plasma melatonin concentrations are utilized as a correlate indicating sleep, and exogenous application has been utilized in the attempt to improve the quality and quantity of sleep. Contemporary studies on the causal effects of melatonin on sleep require drawing of blood, saliva, or urine, however, each of these techniques require effort on the part of the subject, causing deviation from normal sleep patterns. AST proposes to develop a continuous, near real-time, non-invasive monitor for blood borne chemicals, including melatonin (as well as a myriad of other biological molecules), obtained during activity or sleep. This device will be amenable to mass screening of the elderly (and pediatric) population, with the potential for actuator regulated exogenous melatonin administration. PROPOSED COMMERCIAL APPLICATIONS: In addition to utilization for the study of sleep disorders in elderly patients, this device has the potential to monitor concentrations of electrolytes, hormones, therapeutic drugs, drugs of abuse, and environmental toxins in active ambulatory adults and children. Semiconductor manufacture is amenable to mass production at very low cost. This disposable device will be available for the clinical and home health care markets. Long term sales are estimated to be in the millions per year.